What are olives?
Olives are small, oval fruits with a hard, inedible stone in the middle that are traditionally grown across the Mediterranean, but also in California. They come in varying shades of green and black, depending on when they are picked – green being unripe and black, fully ripe.
Once picked, olives are then either made into olive oil, or they are cured and then marinated – otherwise they can taste very bitter. They can then be consumed whole (with the stone removed, or pitted) or they can be used in cooking. Black olives tend to be less bitter than green olives.
Olives can be cured using brine, dry salt or water, and this in turn can then impact their flavour. Sometimes olives are lye-cured, a process whereby raw olives are soaked in an alkaline lye solution, but this can affect their flavour. This is typically used by larger commercial olive producers, but the curing process won’t be shown on food labels, so it is hard to determine if this process has been used.
Olives vary in taste and size depending on their variety, region, and marinade or stuffing. You may find olives labelled from their country such as Spanish or Greek olives, or but you may be more familiar with their specific variety name such as Kalamata, Liguria, Alfonso, Manzanilla or Nocellara.
Nutritional profile of olives
One olive weighs about 4g, and an average serving may be about 15g-20g or about 5 olives which is around 30 calories.
Olives are about 80% water, but are more renowned for their good fat content. Olives are about 10-15% fat, which is primarily a monounsaturated fat known as oleic acid that has been researched for its many health benefits including reducing inflammation and heart disease.
They are low in carbohydrates (with around 1.25g per 20g serving), most of which is made up of fibre (about 0.7g per 20g) and no sugar. They are a low-fibre food and also a low-protein food with negligible amounts in a 20g serving (around 0.15g).
Olives are typically high in salt due the fact that they are cured or packaged in brine or salt water, containing about 0.5g salt per five olives. The NHS recommends no more than 6g salt for adults, and between 2g-5g a day for children depending on their age.
Nutritionally, olives are a good source of a few micronutrients including vitamin E, iron, copper and calcium.
Vitamin E is a powerful antioxidant that helps protect our cells from oxidative damage, and there is evidence that this vitamin may play a role in obesity. Iron is needed by our red blood cells to move oxygen around the body, and copper plays an important role in heart health, reducing the risk of heart disease. Calcium is one of the body’s most abundant minerals and is essential for strong bones and teeth, regulating muscle contractions and making sure our blood clots normally.
Olives are also high in phytonutrients which each carry their own health benefits, including oleuropein which has has been linked to a reduced cancer risk but also gives olive their bitter taste, tyrosol which may have anti-inflammatory benefits and oleonalic acid for its heart health benefits.
How does processing affect the nutrition of olives?
The curing process does remove some of the phytonutrient content of olives, but brine-cured olives are fermented and there is growing research into their positive probiotic actions as a result, which in turn supports good digestive health.
As mentioned above, the natural curing process also increases their salt content.